When fluids are flowing through a conduit such as a pipeline or in a production line from a wellhead, friction resulting from the movement of the fluid over inside surface of the conduit causes a loss in pressure which increases as the downstream distance from the driving source increases. Sometimes it is desirable to increase the flow rate of fluids through conduits, but this cannot always be satisfactorily accomplished by installing additional booster pumps. In production lines, particularly offshore, the cost of additional pumping capacity can become prohibitive. The flow rate of the fluid through the conduit can also be increased by reducing the friction of the fluid in the conduit.
One method of reducing friction loss in fluids moving through a conduit is to inject into the fluid a substance which is capable of reducing the pressure or friction loss of the fluid moving through the conduit. Such substance must not only reduce the friction loss of the fluid, but must be compatible with the fluid and must not interfere with the intended use of the fluid.
A variety of polymeric materials have been used or disclosed for use as "friction loss" additives. For example, friction loss in hydrocarbon liquids flowing through pipelines may be reduced by adding to such liquids small amounts of homopolymers or copolymers of alpha olefins. The use of polyisobutylene as a hydrocarbon liquid friction loss reducing agent has also been taught. In addition, a variety of specific polymers and copolymers have been disclosed for use as friction reducing agents.
Since the friction reducer must be compatible with the fluid to which it is added, oil soluble polymers are ordinarily used to reduce the friction loss in flowing hydrocarbon oils. Where the material being transported is a mixture of water and a hydrocarbon oil particularly when it contains substantial amounts of water, a water soluble polymer is frequently used as the friction reducing agent.